Adult mesenchymal stem cells have the ability to self-renew and differentiate into multiple cell lineages of mesenchymal tissues. Therefore, clinical applications of these cells, such as replacement of damaged tissues or carriers for anti-cancer agents, have been considered. Applications of adult mesenchymal stem cells are still limited to preclinical stage at this time, in part because of rapid aging of these cells ex vivo, which limits their expansion and engineering. Immortalizing mesenchymal stem cells by telomerase transduction is reported to overcome issues associated with accelerated aging. However, their ability of unlimited self-renewal may lead to an out-of-control growth, once they are implanted into tissues. In fact, transformation of telomerase-transduced mesenchymal stem cells was observed in in vitro settings.
Thus, regulation of the growth of adult mesenchymal stem cells is one of the key steps toward their clinical applications.